Component-basis blood collection is a procedure in which blood (whole blood) collected from a donor (blood donor) is separated into blood components by centrifugal separation or membrane separation, a necessary blood component is collected, and the residual blood components are returned to the donor. In the case of component-basis blood collection performed by a centrifugal separation system, particularly a centrifugal bowl system, in order to decrease infestation to the donor, a system in which a single blood collection needle is used, wherein a blood collection step and a blood returning step are repeated alternately, is adopted (refer to, for example, Japanese Laid-Open Patent Publication No. 8-509403 (PCT)).
In normal component-basis blood collection, alcoholic disinfection or the like is carried out. However, even after such a treatment, bacteria present on the skin or subcutaneous bacteria may become mixed in the blood component collection bag together with the blood component.
Depending on the kind of bacteria, the bacteria having thus become mixed may grow even during cold storage of the blood component collection bag, in which the blood component is contained. Therefore, when the blood component is served via transfusion without noticing the bacterial growth, a crisis, such as infectious disease or sepsis in the patient having received the transfusion, may occur.
In red blood cell conservation solutions (S.A.G.M. solutions, OPTISOL solutions, M.A.P. solutions, etc.) in use at present, the pH thereof is set comparatively near to neutral, unlike conventional blood conservation solutions (anticoagulants such as ACD-A solutions or CPD solutions). For this and other reasons, there is a high tendency toward bacterial growth during cold storage.
Such bacteria are often present not only on the surface of the skin but also subcutaneously. Therefore, penetration of such bacteria into the collected blood is difficult to obviate simply by conducting careful disinfection of the skin portion that is punctured by the blood collection needle.
Empirically, it is known that bacteria penetrates (together with debris of the skin, in most cases) mainly into the initial flow of the blood that is collected (the initial blood flow).
However, an apparatus for collecting a blood component is not known, in which the initial blood flow can be removed.
In view of this, in order to remove the initial blood flow, it may be contemplated to provide a line for removing the initial blood flow, which is branched from a branching portion formed in a blood line connected between the blood collection needle and the inlet of the blood separator, and by which the initial blood flow is removed.
In the aforementioned configuration, however, after the removal of the initial blood flow, blood that does not contain any anticoagulant may stagnate at the branching portion, at which the line for removing the initial blood flow branches from the blood line, and such stagnating blood may coagulate. If blood coagulates at the branching portion, such coagulated blood may flow (circulate) in the circuit and become mixed into the blood component in the blood component collection bag during blood collection, or such coagulated blood may be returned to the donor when the residual blood components are returned to the donor. Further, such coagulated blood may plug up the flow passage.